Nut cold hardiness as a factor influencing the restoration of American chestnut in northern latitudes and high elevations
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Canadian Journal of Forest Research. 42: 849-857.
American chestnut (Castanea dentata (Marsh.) Borkh.) was functionally removed as a forest tree by chestnut blight (caused by the fungal pathogen Cryphonectria parasitica (Murr.) Barr). Hybrid-backcross breeding between blight-resistant Chinese chestnut (Castanea mollissima Blume) and American chestnut is used to support species restoration. However, preliminary evidence suggests that backcross material may not have the cold hardiness needed for restoration in the northern portions of the species' range. The cold tolerance of nuts is of concern because reproductive tissues are particularly sensitive to freezing damage. We assessed nut cold tolerance for 16 American chestnut, four Chinese chestnut, and four red oak (Quercus rubra L.) (a native competitor) sources to better assess genetic variation in nut hardiness. We found that Chinese chestnut nuts were less cold tolerant than American chestnut and red oak nuts and that American chestnut sources from the south were less cold tolerant than sources from the north, with significant differences among sources within all regions. We also assessed how sources varied among temperature zones (sources separated by average winter temperature lows at source locations). Sources from the cold temperature zone were more cold tolerant and less variable in hardiness than sources from warm and moderate zones.
Saielli, Thomas M.; Schaberg, Paul G.; Hawley, Gary J.; Halman, Joshua M.; Gurney, Kendra M. 2012. Nut cold hardiness as a factor influencing the restoration of American chestnut in northern latitudes and high elevations. Canadian Journal of Forest Research. 42: 849-857. https://doi.org/10.1139/X2012-033.